Thread rolling apparatus



March 1961 G. s. EIGENBRODE 2,974,550

THREAD ROLLING APPARATUS Filed March 22, 1956 2 Shee+s- Sheet 1 75 v 72 94 74- 'az 0 INVENTOR GLEN N S. EIGENBRODE BY WYW ATTORNEYS March 14, 1961 Filed March 22, 1956 G. S. EIGENBRODE THREAD ROLLING APPARATUS 2 Sheers-Sheet 2 FIG. 6

INVENTOR GLENN S. EIGENBRODE 5% Q/Wi W ATTORNEYS 2,974,550 THREAD ROLLING APPARATUS Glenn S; Eigenbrode, Wayhesboro; P33, assignor to Landis Machine Company, Waynesboro,-Pa., a corporation of Pennsylvania Fil ed Mar. 22, 1956; Ser. No. 573,126

2. Claims. (Cl. 80-6) work" piece.

Devices of this kind have been limited to a large extent to the production of straight or parallel threads on cylindrical work pieces since, prior to the present invention, such tools could not be utilized economically for rolling tapered threads. In such an appliance for rolling straight threads, the rolling dies are rotatably'journalled on shafts whose axes are parallel when the tool is viewed from the direction of the work piece it is approaching. The theoretically correct disposition of theroll axes for rolling tapered threads isthat shown for examplein the United States patent to F. Nell, No. 2,694,322, issued November 16, 1954. There pure rolling movement, without slippage, is obtained by mounting tapered rolling' dies onrelatively inclined axes. The diameters of the Workblank andthe rolling dies are proportional all along thelength of contact and are the same ratio-- in accordance with well .knownbevel ge'ar principles; Y 7

The angle of inclinationbetween each roll axis" and the workaxis isjconsiderably' larger than the angle of taper of the workpiece! For example-if the diametrical ratio of roll to Work piece is 3:1, the angle betweenroll axis-and workpiece axisisapproximately four timesthe taper angle. The expressions angle of taper of' the workpiece and taper angle of' the' work piece areused herein in their generally accepted sense to mean the included angle between diametrically opipbsite' ele} ments on-theworkblank. For example; a work blank having a taper of A of an' inch-tothe foot has a taperangle" or angle of taper of 3 34 minutes 24Fseconds; Since'the roll-to-Work diameter ratio is made as high as possiblein order to:decrease the wear per unit of area on-the rolling surface and thus to increase the-life' ofthe rolls; the angle of inclination of the roll axes is' quite large where wear rate is an important factor.

With this prior system of rolling the" relatively large angle of inclination'of the'roll" axis results in a substaiif tially' largerframe'than is required for a worm" the roll axes areparallel: Oftentheres'ultant frame is too'ilarge to pe r'mit 'its usewitliin the usuallyc l'oseico'n-" fines of the working station ori the automaticscr'ew ma chine to which the tool'is applied.

Since,-in-thisprior system the axes rwgikpi ceand bothrolls must meet at a common apex, thefframeoff the tool cannot be d'esignedfor any significant diametrical adjustments Accordingly any'chan'ge in rolling diameter beyond'mere accuracy adjustment requ'i'rs ,a' complete" each work diameter andtaper greatly increases the-" first the" tapered rolls are 2,974,550 Patented Mar. 14, 1961 of the roll operates upon the smaller end of the work and vice versa. Such lack of proportion between adjacent diameters of work piece and rolls makes uniform surface speed of the contacting surfaces impossible. Undesirable slippage thus results between the surfaces of rolls and work piece except at the lateral mid-point thereof where pure rolling action occurs. Thus while this particular construction avoids the above-described disadvantages of tool size andlack of adjustability it has a rolling action so defective as to render the roll life and consequent replacement cost economically prohibitive.

In the rolling apparatus of the present invention cylindrical rolls are employed to roll threads on a tapered work piece and are mounted on axes which. are parallel to the angle of taper. By this means the disadvantages of the prior constructions described above are obviated or minimized' The angle of inclination of the roll axes with respect to the work axis is very much smaller than is the case with the construction having theoretically perfect rolling action. Therefore the size of the holder or frame is never unduly large. The angle of'inclination of the roll axes with respect to the work axis is constant regardless of diameter so that the frame can be made adjustable for a range of diameters. Although unequal peripheral speeds are present along the thread length due to the unequal diameter ratios, the effect thereof is relatively unimportantin comparison with tapered rolls mounted on parallel axes. in the device of the present invention-is as much as 6 times as great as in a construction having tapered rolls on parallel axes. Experience has shown that the tool of the present invention is commercially acceptable and economically superior.

An object of the invention is to provide atwo-roll mechanism for rolling a tapered threadwhile moving laterally toward the axis of a work piece in which the two rolls are substantially cylindrical and are mounted on axes which are parallel to the taper of the work piece when viewed from the direction of the work piece.

Another object is to'provide a mechanism of the class.

7 which is adapted to the non-parallelism of the roll axes.

Otheiwobjects and advantages of the invention will be apparent from'the following description of an exemplary" embodiment thereof and from the accompanying draw ings-in which: g g a l Figure 1 is a side elevation of the assembled tool;-

1 with the supporting shank removed; V

Figure 2 is a sectional View along line 2f2-of' Figure Figure l; a g a g Figured is a fragmentary sectional: view along line 6 -6 .of Figur'4; '7 Figure- 7 is a fragmentary'sectional viewalongline- 7,-7 of Figure2; and a l I Figure 8 is av fragmentary sectional view al-ongc'line.

88 I of Figure, 2.

mounted withwtheir axes parallel -so tsamnea'arger end 5' The fundamental structure 10f therolling' 'tooleinbody ing the'present'invention is the same as' that sh'ownf and; described in co-pending application Serial No. 380558; filed September 16; 1953, now abandoned, and reference For example, the roll life Figure 3 is a sectional view along line 3-3 of Figure;

Figure 4 is a sectional view along-line; 4--41of Figure F'g ure 5 is" a partial sectional view along line-55 of;-

may be had to that application for details not completely described herein.

The tool embodying the invention comprises a holder 20 which is adapted to be secured to a cam-operated tool slide of an automatic'screw machine (not shown), for example, which slide moves in a path perpendicular to the axis of the rotating work piece W. The holder 20 is provided with tWo fiat, forwardly projecting arms 22 and 24 (Figures 1 and having aligned openings near their forward extremities through which a pivot pin 26 is passed. A flange 28 is formed near one end of pin 26, outwardly of the arm 22. A screw 30, threaded into the side of arm 22 overlaps a portion of flange 28 to retain the pin 26 axially in position. A knurled extension 32 may be added to the pin 26, outwardly of the flange 28, for manual removal of the pin 26 after removal of the screw 30.

Upper and lower frame members 34 and 36, respectively, are journalled for pivotal movement on a bushing 38 which is mounted on the pin 26 between the arms 22 and 24. The upper frame member 34 is provided with spaced depending portions 40 which lie adjacent the opposite sides of an upward extension 42 of lower frame member 36, the bushing 38 passing through portions 48 and extension 42. The ends of the bushing 38 should be flared slightly outwardly after assembly of the members 34 and 36 to prevent relative axial movement between the frame members and the bushing.

Aligned recesses 44 of rectangular cross section are formed in the rear surfaces of frame members 34 and 36 to receive a strap member 46 (Figures 4 and 6). Screws 48 and 50 secure the strap 46 to frame members 34 and 36 respectively and effectively prevent rotation of members 34 and 36 relative to each other about pin 26 while the deviceis in operation. The openings in strap 46 for the screws 48 and 50 are slightly elongated to permit the strap to move relatively to the screws when they are loosened.

As will be described more in detail later, the thread rolling dies or rolls 52 and 54 are mounted, with their rolling surfaces opposed, in the frame members 34 and 36 respectively. To change the spacing between the opposed rolls and thus to arrange the tool for operation upon a work piece of a different diameter it is necessary to rotate frame members 34 and 36 relative to each other and to fix them in the new position. This is done by removing the strap 46 and replacing it with another of different length. To insure that the set position does not change under rolling pressure, a plug 56 is seated in an opening 58 adjacent each end of strap 46 andeach plug 56 has a beveled side 60 to engage an end of the strap. A second pair of openings 62 (Figure 6). onev in each of the frame members 34 and 36 extend from a side of said frame members and communicate with openings 58 in perpendicular relation thereto. A plug 64 is seated in each of the openings 62 and has a bevel on its inner end to engage a complementary bevel on the inner end of the plug 56. A screw 66 is threadedly engaged in each of openings 62 to urge the plug 64 inwardly against the plug 56 and thus lock the strap 46 in position. If either of the screws 48 or 50 is loosened, the corresponding screw 66 may be used to effect a small amount of relative movement between strap 46 and one of the frame members, thus effecting a fine adjustment of the space between the opposed rolls 52' and 54 and therefore of the finished work diameter.

A relatively wide slot or recess 68 (Figure 2 and 4) is formed vertically through frame members 34 and 36 to provide space for the threading rolls 52 and 54 which are journalled for rotation on shafts 70 and 72 respectively. Each of these shafts is supported at one end by a flanged bushing 74 stationarily mounted in bores 75 extending through the side of each of the frame members 34 and 36 with its outer end surface substantially flush the surface of theframe member. As shown in Figures 2 and 8, an arcuate groove 76 is formed about the periphery of each bushing 74. A threaded opening 78 is provided in each frame member and extends tangentially to the bushing 74 to enable a screw 80 to be inserted in the opening 78 and engage a portion of the circumferential groove 76 to prevent axial movement of the bushing 74. A pin 821s passed through the flange of each bushing 74 and is embedded in the side of the respective frame members 34 and 36 for the purpose of preventing rotation of the bushings. Thesarne pin 82 engages a suitable opening in a wear plate 84 mounted on each of the shafts 70 and 72 between an end surface of the threading roll on that shaft and the side wall of the recess 68.-

Each of the shafts 70 and 72 is supported at the other end by a bushing 86 stationarily mounted in bores 87 extending through the sides of the respective frame members. Bores 87 are coaxial with bores 75. A notch 88 having inclined sides is formed in the periphery of each bushing 86. As shown in Figures 1 and 2, a screw 90 is threadedly engaged in each frame member 34 and 36 with its axis parallel to that of the adjacent bushing 86 and with its head adapted to engage the notch 88. Thus each screw 90 serves to retain a bushing 86 in position both rotatively and axially. Inwardly of the bushings 86, the openings in frame members 34 and 36 through which the shafts 70 and 72 pass are formed with flat sides 92 (Figure 7) to fit closely similarly flattened portions 94 on the end of each shaft. The shafts are thus prevented from rotating relatively to the frame members 34 and 36.

The opening in the respective frame members for each of the shafts 70 and 72, inwardly of the above described keying engagement and communicating with the recess 68, is enlarged to accommodate a gear 96 which is journalled for rotation on the shaft. As shown in Fig ure 2, each gear 96 has a hub 98 extending axially toward the adjacent threading roll 52 or 54. Each hub 98 is provided with two diametrically opposite projections 100 which, as in the above-mentioned co-pending application are so dimensioned as to fit within slots 102 in the associated roll with an appreciable clearance. Also as before, cylindrical spring wires 103 project from hub 98 ad acent the sides of projections 100 to occupy this clearance and to constitute a resilient keying connection between roll and gear.

As shown in Figure 3, the roll gears 96 are connected for uniform rotation by a series of three spur gears 104, 104, 106 for which suitable recesses 108 are provided in frame members 34 and 36. The central gear 106 is ournalled for rotation upon a bushing 110 on the shaft 26 and is held in position axially by a flanged cap member 112 also surrounding shaft 26. The remaining idler gears 104, 104 are rotatively mounted upon bushings 114 on stud shafts 116 which are embedded in the frame members 34 and 36 and protrude outwardly centrally of the recesses 108. Flanged cap members 118 are provided to close the recesses 108 and to retain the idler gears 104, 104 in proper axial position. As shown in Flgures l and 5 the central cap member 112 overlaps both cap members 118 to retain the latter in position. The cap member 112 is in turn prevented from moving axially by the engagement of the head of a screw 120 with a suitable notch in the flange of said cap member. A bushing 122 (Figure 2) surrounds each gear hub 98 and 1s provided with a flange which extends into the recess 68 to form a wear plate for the adjacent threading roll. A pin 124, frictionally fitted in each frame member '34, .36 and extending into suitable notches in each bush ng 122, prevents rotation of said bushing. The bushings 122 and plates 84, described above, closely define the axial position of threading rolls 52 and 54 but a small amount of clearance is provided for purposes of safety and to allow a slight endwise movement of the rolls as they are withdrawn from the work piece after completion of the thread rolling operation.

As shown in Figure 2, the recesses in bushings 74 and 86 for receiving the ends of shafts 70 and 72 are so located and inclined as to dispose the shafts parallel to the tapered side surfaces of the work piece to be rolled. That is to say, if the work piece has a taper of per foot, each shaft axis is inclined at an angle of 147 with respect to the Work piece axis. The threading rolls 52 and 54 are of uniform diameter over the threading portion thereof.

To permit the threading rolls to function properly the surfaces of the wear plates 84 facing the threading rolls are normal to the axes of shafts 70 and 72. Also the surfaces of the bushings 122 facing the threading roll from the oppositeside are similarly inclined. The hub 98 of each roll gear 96 may be tapered from left to right as seen in Figure 2 in order to clear properly the interior of bushing 122 Each rollgear 96 is formed with teeth inclined at the taper angle with respect to the axis of the gear so as to be parallel to and mesh properly with the spur teeth on idler gear 104. The outwardly facing side surface of each gear 96 may also be beveled at the same angle to avoid interference with the bottom of the gear recess.

It will be evident therefore that the tool is capable of being employed on tapered threads with the same freedom that a similar tool having parallel roll axes is employed on straight threads. Diametrical changes can be made and rolls of various diameters and pitches may be interchangeably mounted on the same shafts if the angle of taper of the work piece does not change. For work of a different taper, or of zero taper, i.e. work with straight threads, it is necessary to replace only the bushings 74 and 86, roll gears 96 and Wear plates 84 and 122. The frame and all other parts may be used for all tapers within the range for which the tool is constructed.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

11. A thread rolling device for rolling tapered threads on a tapered work piece comprising a pair of jaws pivotally mounted in a frame each of said jaws, having a pair of co-axial bores, the common axis of which is parallel with the work blank axis, said bores opening through the walls of a recess, said walls being normal to the axis of said bores, a bushing in each bore in each jaw, the bushings in each jaw having coaxial openings, the common axis of which is inclined with respect to the work blank axis at the angle of taper of the work blank, shafts mounted in each of said bushings and extending across said recesses, cylindrical rolls having peripheral thread forming serrations mounted on the respective shafts in said recesses and having end surfaces normal to the axis of said shaft, and wear plates positioned between one end surface of each of said rolls and the adjacent wall of said recess, the surface of said Wear plate contacting the end of the roll being normal to the roll shaft axis.

2. A thread rolling device for rolling tapered threads on a tapered Work blank comprising, a pair of jaws pivotally mounted in a frame, said jaws each having a pair of coaxial bores, the common axis of which is parallel with the work blank axis, said bores opening through the walls of a recess, said Walls being normal to the axis of said bores, bushings non-rotatably mounted in each of said bores, the pairs of bushings in the respective jaws having coaxial openings, the common axis of which is inclined with respect to the work blank axis at the angle of taper of the work blank, shafts mounted in said bushings and extending across said recesses, cylindrical rolls having peripheral thread forming serrations mounted on the respective shafts in said recesses and having end surfaces normal to the axis of said shafts, wear plates positioned between one end surface of each of said rolls and the adjacent wall of said recess, the surface of said wear plate contacting the end of the roll being normal to the roll shaft axis, respective main gears mounted on said shafts and non-rotatably associated with the respective rolls, and a series of idler gears connecting said main gears, said main gears having gear teeth inclined with respect to the gear axes at the angle of taper of the work blank.

References Cited in the file of this patent UNITED STATES PATENTS 2,679,773 Scott June 1, 1954 2,694,322 Nell Nov. 16, 1954 2,771,799 Batchelder Nov. 27, 1956 2,781,586 Eigenbrode Feb. 19, 1957 OTHER REFERENCES Landis: Thread Tips, January 1, 5, 5 pages.

Parts List and Operating Instructions for Lanroll Thread Rolling Attachments, Landis, September 1955, 15 pages. 

